Biocidal compositions and use thereof

ABSTRACT

A fungicidal composition and method for inhibiting and controlling the growth of the capsulated, facultative bacterium, Trichoderma viride, are disclosed. The compositions comprise 2-(2-bromo-2-nitroethenyl) furan and diiodomethyl-p-tolylsulfone. The method comprises adding from 1 part to about 500 parts composition to the aqueous system for which treatment is desired.

FIELD OF THE INVENTION

This invention relates to compositions and methods for controlling thegrowth of Trichoderma viride.

BACKGROUND OF THE INVENTION

The formation of slimes by microorganisms is a problem that isencountered in many aqueous systems. For example, the problem is notonly found in natural waters such as lagoons, lakes, ponds, etc., andconfined waters as in pools, but also in such industrial systems ascooling water systems, air washer systems and pulp and paper millsystems. All possess conditions which are conducive to the growth andreproduction of slime-forming microorganisms. In both once-through andrecirculating cooling systems, for example, which employ largequantities of water as a cooling medium, the formation of slime bymicroorganisms is an extensive and constant problem.

Airborne organisms are readily entrained in the water from coolingtowers and find this warm medium an ideal environment for growth andmultiplication. Aerobic and heliotropic organisms flourish on the towerproper while other organisms colonize and grow in such areas as thetower sump and the piping and passages of the cooling system. The slimeformation not only aids in the deterioration of the tower structure inthe case of wooden towers, but also promotes corrosion when it depositson metal surfaces. Slime carried through the cooling system plugs andfouls lines, valves, strainers, etc., and deposits on heat exchangesurfaces. In the latter case, the impedance of heat transfer can greatlyreduce the efficiency of the cooling system.

In pulp and paper mill systems, slime formed by microorganisms iscommonly encountered and causes fouling, plugging, or corrosion of thesystem. The slime also becomes entrained in the paper produced to causebreakouts on the paper machines, which results in work stoppages and theloss of production time. The slime is also responsible for unsightlyblemishes in the final product, which result in rejects and wastedoutput.

The previously discussed problems have resulted in the extensiveutilization of biocides in cooling water and pulp and paper millsystems. Materials which have enjoyed widespread use in suchapplications include chlorine, chlorinated phenols, organs-bromines, andvarious organo-sulfur compounds. All of these compounds are generallyuseful for this purpose but each is attended by a variety ofimpediments. For example, chlorination is limited both by its specifictoxicity for slime-forming organisms at economic levels and by thetendency of chlorine to react, which results in the expenditure of thechlorine before its full biocidal function is achieved. Other biocidesare attended by odor problems and hazards with respect to storage, useor handling which limit their utility. To date, no one compound or typeof compound has achieved a clearly established predominance with respectto the applications discussed. Likewise, lagoons, ponds, lakes, and evenpools, either used for pleasure purposes or used for industrial purposesfor the disposal and storage of industrial wastes, become, during thewarm weather, besieged by slime due to microorganism growth andreproduction. In the case of industrial storage or disposal ofindustrial materials, the microorganisms cause additional problems whichmust be eliminated prior to the materials' use or disposal of the waste.

Naturally, economy is a major consideration with respect to all of thesebiocides. Such economic considerations attach to both the cost of thebiocide and the expense of its application. The cost performance indexof any biocide is derived from the basic cost of the material, itseffectiveness per unit of weight, the duration of its biocidal orbiostatic effect in the system treated, and the ease and frequency ofits addition to the system treated. To date, none of the commerciallyavailable biocides has exhibited a prolonged biocidal effect. Instead,their effectiveness is rapidly reduced as a result of exposure tophysical conditions such as temperature, association with ingredientscontained by the system toward which they exhibit an affinity orsubstantivity, etc., with a resultant restriction or elimination oftheir biocidal effectiveness, or by dilution.

As a consequence, the use of such biocides involves their continuous orfrequent addition to systems to be treated and their addition tomultiple points or zones in the systems to be treated. Accordingly, thecost of the biocide and the labor cost of applying it are considerable.In other instances, the difficulty of access to the zone in which slimeformation is experienced precludes the effective use of a biocide. Forexample, if in a particular system there is no access to an area atwhich slime formation occurs the biocide can only be applied at a pointwhich is upstream in the flow system. However, the physical or chemicalconditions, e.g., chemical reactivity, thermal degradation, etc., whichexist between the point at which the biocide may be added to the systemand the point at which its biocidal effect is desired render theeffective use of a biocide impossible.

Similarly, in a system experiencing relatively slow flow, such as apaper mill, if a biocide is added at the beginning of the system, itsbiocidal effect may be completely dissipated before it has reached allof the points at which this effect is desired or required. As aconsequence, the biocide must be added at multiple points, and even thena diminishing biocidal effect will be experienced between one point ofaddition to the system and the next point downstream at which thebiocides may be added. In addition to the increased cost of utilizingand maintaining multiple feed points, gross ineconomies with respect tothe cost of the biocide are experienced. Specifically, at each point ofaddition, an excess of the biocide is added to the system in order tocompensate for that portion of the biocide which will be expended inreacting with other constituents present in the system or experiencephysical changes which impair its biocidal activity.

SUMMARY OF THE INVENTION

The present inventors have discovered that a composition of2-(2-bromo-2-nitroethenyl) furan (BNEF) and diiodomethyltolylsulfone(DMTS) is effective as a biocide directed towards controllingTrichoderma viride.

DESCRIPTION OF THE RELATED ART

U.S. Pat. No. 5,158,972, Whitekettle et al., teaches the use of2-(2-bromo-2-nitroethenyl) furan and glutaraldehyde to control thegrowth of Kiebsiella pneumoniae. U.S. Pat. No. 4,965,377, McCoy et al.,teaches a process for forming 2-(2-bromo-2-nitroethenyl) furan whichproved effective as an antimicrobial agent.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to compositions and methods for bacterialinhibition comprising a synergistic mixture of (A)2-(2-bromo-2-nitroethenyl) furan and (B) diiodomethyl-p-tolylsulfone.

It has been found that mixtures of 2-(2-bromo-2-nitroethenyl) furan(BNEF) diiodomethyl-p-tolylsulfone (DMTS) are especially efficacious incontrolling the growth of fungal microbes, specifically the Trichodermaviride species. This particular species is a member of the capsulated,facultative class of bacteria and is generally present in air, water andsoil. These bacteria continually contaminate open cooling systems andpulping and papermaking systems and are among the most common slimeformers. The slime may be viewed as being a mass of agglomerated cellsstuck together by the cementing action of the gelatinous polysaccharideor proteinacious secretions around each cell. The slimy mass entrapsother debris, restricts water flow and heat transfer, and may serve as asite for corrosion.

The fact that the Trichoderma species used in the tests is a fungalspecies is important, as by definition, such fungi may thrive underaerobic conditions. Accordingly, by reason of demonstrated efficacy inthe growth inhibition of this particular species, one can expect similargrowth inhibition attributes when aerobic or anaerobic bacterial speciesare encountered. It is also expected that these compositions willexhibit similar growth inhibition attributes when bacteria and algaespecies are encountered.

In accordance with the present invention, the combined BNEF and DMTStreatment may be added to the desired aqueous system in need of biocidaltreatment, in an amount of from about 1 to about 500 parts of thecombined treatment to one million parts (by weight) of the aqueousmedium. Preferably, about 5 to about 100 parts of the combined treatmentper one million parts (by weight) of the aqueous medium is added.

The combined treatment is added, for example, to cooling water systems,paper and pulp mill systems, pools, ponds, lagoons, lakes, etc., tocontrol the formation of bacterial microorganisms, which may becontained by, or which may become entrained in, the system to betreated. It has been found that the compositions and methods ofutilization of the treatment are efficacious in controlling the fungalorganism, Trichoderma viride, which may populate these systems. Thecombined treatment composition and method of the present invention willalso be efficacious in inhibiting and controlling all types of aerobicand anaerobic bacteria.

Surprisingly, it has been found that when the ingredients are mixed, incertain instances, the resulting mixtures possess a higher degree offungicidal activity than that of the individual ingredients comprisingthe mixture. Accordingly, it is possible to produce a highly efficaciousfungicide. Because of the enhanced activity of the mixture, the totalquantity of the fungal treatment may be reduced. In addition, the highdegree fungicidal effectiveness which is provided by each of theingredients may be exploited without use of higher concentrations ofeach.

The invention will now be further described with reference to a numberof specific examples which are to be regarded solely as beingillustrative, and not as restricting the scope of the invention.

EXAMPLES

BNEF and DMTS were added in varying ratios and over a wide range ofconcentrations to a liquid nutrient medium which was subsequentlyinoculated with a standard volume of a suspension of the fungal organismTrichoderma viride. Growth was measured by determining the amount ofradioactivity accumulated by the cells when 14C-glucose was added as thesole source of carbon in the nutrient medium. The effect of the biocidechemicals, alone and in combination, is to reduce the rate and amount of14C incorporation into the cells during incubation, as compared tocontrols not treated with the chemicals. Additions of the biocides,alone and in varying combinations and concentrations, were madeaccording to the accepted "checkerboard" technique described by M. T.Kelley and J. M. Matsen, Antimicrobial Agents and Chemotherapy. 9:440(1976). Following a two hour incubation, the amount of radioactivityincorporated in the cells was determined by counting (14C liquidscintillation procedures) for all treated and untreated samples.

The percent reduction of each treated sample was calculated from therelationship: ##EQU1##

Plotting the % reduction of 14C level against the concentration of eachbiocide acting alone results in a dose-response curve, from which thebiocide dose necessary to achieve any given % reduction can beinterpolated.

Synergism was determined by the method of calculation described by F. C.Kull, P. C. Eisman, H. D. Sylwestrowicz and R. L. Mayer, AppliedMicrobiology 9,538 (1961) using the relationship: ##EQU2## wherein:Q_(a) =quantity of compound A, acting alone, producing an end point

Q_(b) =quantity of compound B, acting alone, producing an end point

Q_(A) =quantity of compound A in mixture, producing an end point

Q_(B) =quantity of compound B in mixture, producing an end point

The end point used in the calculations is the % reduction caused by eachmixture of A and B. Q_(A) and Q_(B) are the individual concentrations inthe A/B mixture causing a given % reduction. Q_(a) and Q_(b) aredetermined by interpolation from the respective dose response curves ofA and B as those concentrations of A and B acting alone which producethe same % reduction as each specific mixture produced.

Dose-response curves for each active acting alone were determined bylinear regression analysis of the dose-response data. Data were fittedto a curve represented by the equation shown with each data set. Afterlinearizing the data, the contributions of each biocide component in thebiocide mixtures to the inhibition of radioisotope uptake weredetermined by interpolation with the dose-response curve of therespective biocide. If, for example, quantities of Q_(A) plus Q_(B) aresufficient to give a 50% reduction in 14C content, Q_(a) and Q_(b) arethose quantities of A or B acting alone, respectively, found to give 50%reduction in 14C content. A synergism index (SI) is calculated for eachcombination of A and B.

Where the SI is less than 1, synergism exists. Where the SI=1,additivity exists. Where SI is greater than 1, antagonism exists.

The data in the following tables come from treating Trichoderma viride,a common nuisance fungal type found in industrial cooling waters and inpulping and papermaking systems, with varying ratios and concentrationsof BNEF and NTBC. Shown for each combination is the % reduction of 14Ccontent (% I), the calculated SI, and the weight ratio of BNEF and DMTS.

                  TABLE I                                                         ______________________________________                                        DMTS vs. BNEF                                                                 ppm      ppm     Ratio                                                        DMTS     BNEF    DMTS:BNEF     % I  SI                                        ______________________________________                                        6        0       100:0         96                                             3        0       100:0         93                                             1.5      0       100:0         90                                             0.75     0       100:0         77                                             0.38     0       100:0         60                                             0.19     0       100:0         54                                             0        40      0:100         91                                             0        20      0.100         83                                             0        5       0:100         71                                             0        2.5     0:100         62                                             0        1.25    0:100         52                                             0        0.63    0:100         38                                             6        40      1:6.7         98   2.14                                      6        20      1:3.3         97   1.86                                      6        5       1.2:1         96   1.64                                      6        2.5     2.4:1         96   1.65                                      6        1.25    4.8:1         96   1.66                                      6        0.63    9.5:1         96   1.62                                      3        40      1:13.3        92   2.21                                      3        20      1:6.7         94   1.44                                      3        5       1:1.7         93   1.11                                      3        2.5     1.2:1         94   0.97                                      3        1.25    2.4:1         93   1.04                                      3        0.63    4.8:1         94   0.96                                      1.5      40      1:26.7        86   2.64                                      1.5      20      1:13.3        89   1.38                                      1.5      5       1:3.3         92   0.69*                                     1.5      2.5     1:1.7         91   0.65*                                     1.5      1.25    1.2:1         89   0.70*                                     1.5      0.63    2.4:1         40   0.66*                                     0.75     40      1:53.3        94   1.12                                      0.75     20      1:26.7        91   0.86*                                     0.75     5       1:6.7         85   0.66*                                     0.75     2.5     1:3.3         83   0.65*                                     0.75     1.25    1:1.7         80   0.74*                                     0.75     0.63    1.2:1         77   0.83*                                     0.38     40      1:105.3       94   1.06                                      0.38     20      1:52.6        91   0.74*                                     0.38     5       1:13.2        81   0.63*                                     0.38     2.5     1:6.6         78   0.57*                                     0.38     1.25    1:3.3         71   0.79*                                     0.38     0.63    1:1.7         61   1.41                                      0.19     40      1:210.5       91   1.25                                      0.19     20      1:105.3       88   0.82*                                     0.19     5       1:26.3        78   0.60*                                     0.19     2.5     1:13.2        69   0.78*                                     0.19     1.25    1:6.6         61   1.01                                      0.19     0.63    1:3.3         54   1.34                                      ______________________________________                                    

                  TABLE II                                                        ______________________________________                                        DMTS vs. BNEF                                                                 ppm      ppm     Ratio                                                        DMTS     BNEF    DMTS:BNEF     % I  SI                                        ______________________________________                                        6        0       100:0         95                                             3        0       100:0         92                                             1.5      0       100:0         88                                             0.75     0       100:0         79                                             0.38     0       100:0         58                                             0.19     0       100:0         34                                             0        40      0:100         86                                             0        20      0.100         76                                             0        5       0:100         54                                             0        2.5     0:100         38                                             0        1.25    0:100         29                                             0        0.63    0:100         17                                             6        40      1:6.7         97   2.31                                      6        20      1:3.3         95   2.32                                      6        5       1.2:1         96   1.95                                      6        2.5     2.4:1         96   1.96                                      6        1.25    4.8:1         95   1.98                                      6        0.63    9.5:1         95   1.96                                      3        40      1:13.3        97   1.46                                      3        20      1:6.7         96   1.24                                      3        5       1:1.7         95   1.07                                      3        2.5     1.2:1         94   1.07                                      3        1.25    2.4:1         94   1.07                                      3        0.63    4.8:1         94   1.07                                      1.5      40      1:26.7        96   1.07                                      1.5      20      1:13.3        94   0.84*                                     1.5      5       1:3.3         92   0.68*                                     1.5      2.5     1:1.7         91   0.65*                                     1.5      1.25    1.2:1         89   0.69*                                     1.5      0.63    2.4:1         88   0.72*                                     0.75     40      1:53.3        94   0.93*                                     0.75     20      1:26.7        93   0.64*                                     0.75     5       1:6.7         85   0.54*                                     0.75     2.5     1:3.3         81   0.60*                                     0.75     1.25    1:1.7         80   0.57*                                     0.75     0.63    1.2:1         81   0.52*                                     0.38     40      1:105.3       93   0.84*                                     0.38     20      1:52.6        89   0.60*                                     0.38     5       1:13.2        77   0.54*                                     0.38     2.5     1:6.6         62   0.93*                                     0.38     1.25    1:3.3         51   1.43                                      0.38     0.63    1:1.7         63   0.79*                                     0.19     40      1:210.5       93   0.78*                                     0.19     25      1:105.3       86   0.63*                                     0.19     5       1:26.3        75   0.43*                                     0.19     2.5     1:13.2        54   0.94*                                     0.19     1.25    1:6.6         46   1.12                                      0.19     0.63    1:3.3         41   1.21                                      ______________________________________                                    

Asterisks in the SI column indicate synergistic combinations inaccordance with the Kull method supra.

In Tables I and II, differences seen between the replicates ire due tonormal experimental variance.

In accordance with Tables I-II supra., unexpected results occurred morefrequently within the product ratios of DMTS to BNEF of from about 2.4:1to about 1:105.3 . Since the DMTS product contains 40% active biocidalcomponent and the BNEF product contains 10% active biocidal component,unexpected results appear more frequently within the range of activecomponent (100% actives basis) of DMTS:BNEF of about 9.6:1 to about1:26.3. At present, the most preferred ratio comprises a weight ratio ofactive component of about 1:1 DMTS:BNEF.

While this invention has been described with respect to particularembodiments thereof, it is apparent that numerous other forms andmodifications of this invention will be obvious to those skilled in theart. The appended claims and this invention generally should beconstrued to cover all such obvious forms and modifications which arewithin the true spirit and scope of the present invention.

Having thus described the invention, what we claim is:
 1. A fungalinhibiting composition comprising a synergistic mixture of (A)diiodomethyl-p-tolylsulfone and (B) 2-(2-bromo-2-nitroethenyl) furanwherein the weight ratio of (A):(B) (100% actives basis) is from about9.6:1 to about 1:26.3.
 2. The composition as claimed in claim 1 whereinthe weight ratio of (A):(B) is about 1:1.
 3. A method for controllingthe growth of Trichoderma viride fungi in an aqueous system whichcomprises adding to said system from about from about I to 500 parts perweight of a composition per one million parts per weight of said aqueoussystem, said composition comprising a synergistic mixture of (A)diiodomethyl-p-tolylsulfone and (B) 2-(2-bromo-2-nitroethenyl) furan,the weight ratio of (A):(B) (100% actives basis) being from about 9.6:1to about 1:26.3.
 4. The method as recited in claim 3 wherein the weightratio of (A):(B) is about 1:1.
 5. The method as claimed in claim 3wherein said composition is added to said system in an amount from about5 to about 100 parts per million of said aqueous system.
 6. The methodas recited in claim 3 wherein said aqueous system comprises a coolingwater system.
 7. The method as recited in claim 3 wherein said aqueoussystem comprises a pulping and papermaking system.